School me on 302 & 351

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School me on 302 & 351

November 17, 2013, 02:30:04 PM

Are the heads interchangeable? I currently have a 302 with gt40p heads they have a ton of work done to them. I might be going to a 351 will they just bolt on? Thanks

School me on 302 & 351

Reply #1 – November 17, 2013, 03:58:00 PM

I believe so. I have heard some say that certain 302 heads need the bolt holes enlarged. I am sure somebody with more experience will chime in.

School me on 302 & 351

Reply #2 – November 17, 2013, 04:02:46 PM

Quote from: slowbird;424513

Are the heads interchangeable? I currently have a 302 with gt40p heads they have a ton of work done to them. I might be going to a 351 will they just bolt on? Thanks

yes and no. the head gaskets are basically the same, there might be a steam hole that needs to be drilled in the head or block depending on the year block you are using. the 351w used 1/2" head bolts, where as the 302 used 7/16" head bolts. so using 302 heads on a 351w means a tighter clearance between teh bolts and the head bolt openings, not really an issue unless you are using head studs. you also need to use a different 351w intake. remember that the early intakes on the 351w used an L shaped coolant passage in the head, as well as two extra bolt holes for the intake on each side. later ones, i think after 1974 or so, changes over to the 302 style intake with a more normal coolant passage and six bolt holes per side. also note that 351w heads generally have large combustion chambers to keep the compression ratio down to about 9.5:1, and using the 302 heads with their smaller chambers can push the compression ratio up about 1.5 points, so be aware of that also. do some serious calc time on a compression ratio calculator and be sure of where you are going to be compression ratio wise before running the combination.

School me on 302 & 351

Reply #3 – November 17, 2013, 09:53:45 PM

Once you redrill those gt40p's for the larger head bolts they might be hard to sell once you get bored with the combo.

You might want to go with a trickflow, victor jr, or afr alum head if you can, you'll also be adding the extra weight with the 351..and you could offset some of that with the lighter head. Plus the larger valves and better flow would be put to good use! :)

School me on 302 & 351

Reply #4 – November 18, 2013, 01:53:26 AM

Sell the ported P's and do as Bob suggested. Better flow, even thought the '40s were ported, less weight, and all that.
Pick a good cam, and put it together.

But yes, in a pinch, you could use the GT40P's on a 351w. There used to be available the special shanked bolts enable the 7/16" sized heads to be used on the 351 blocks...might try that route if you can't swing the nice aftermarket parts yet. Better than stock E7's by any stretch.

School me on 302 & 351

Reply #5 – November 18, 2013, 08:16:37 AM

You will make 302 power on a 351 with 302 parts.

Drilling the head bolt/stud to 1/2" is not a big deal as ARP makes the bushings to go from 1/2" to 7/16".

Darren

School me on 302 & 351

Reply #6 – November 18, 2013, 11:39:11 AM

Ya if I had the money I would deff get some aluminum heads.. but unfortunately have to make use of what I got. Just figured I could get a 351 for the same price of a 302

School me on 302 & 351

Reply #7 – November 18, 2013, 02:01:33 PM

and a 351w sounds nice to have, i even seriously considered building one, still might for something one day, but unless you are going drag racing and need the cubes, the 302 will do very nicely when properly built.

School me on 302 & 351

Reply #8 – November 18, 2013, 04:18:20 PM

Factor in the added cost of new 351w-specific parts like intake, headers, and probably working over or replacing your existing X/H pipe, and it might be cost effective to go with a good stroker kit. You'll also need a new pan, and if you really get powerful, probably a stronger transmission too.

You know how it is...the vehicular domino effect.

School me on 302 & 351

Reply #9 – November 18, 2013, 07:55:48 PM

Trans I am not worried about. The c4 in there is fully built. Car is mainly drag raced.. Unfortunately I hurt the motor last time out.. Looks like I'll just grab another junk yard 302 lol... Thanks again for the info

School me on 302 & 351

Reply #10 – November 18, 2013, 08:06:30 PM

351 lightnings came with gt40 heads

School me on 302 & 351

Reply #11 – November 18, 2013, 10:50:48 PM

And they ran like a dog for all the additional cubes. Change the heads on them and they all of a sudden woke up. 302 parts on a 351 and 302 power.

Darren

School me on 302 & 351

Reply #12 – November 18, 2013, 11:12:14 PM

^Yup. A friend had one, had some bolt ons when he bought it. His brother sold him a set of some brand (forget which, now) of alum. heads, really woke that sumbitch up. Was pretty unreal to ride in a truck that...sudden.

I know it doesn't mean jack shiznit, but that thing would break the back hides loose at any speed, any time, simply by matting the fun pedal. I was with him one day, going down the local 2 lane highway doing a double nickel, he floored it and it spun the tires easily. I don't know the specs, but it had aftermarket heads, cam, intake and exhaust. Was n/a, and had a shift kit as well. Probably the rear gear was non stock. Other than the idle note, it was as docile as any 302 F series if you drove it like a little old lady.

I want one. About had one last winter, but I waited too long to call the dude and someone else had laid a deposit down on it. me for being hesitant.

Sorry for the sideways post..

School me on 302 & 351

Reply #13 – November 18, 2013, 11:24:26 PM

The GT40 lightning heads then the 302 versions....bigger combustion chamber. ..67cc IIRC

But the old saying 302 power heads on a 351 seams to apply. If you r NA I would go with better heads! But with boost those heads will make power....

Travis

School me on 302 & 351

Reply #14 – November 18, 2013, 11:25:01 PM

So true